Pyrogenic carbon is widely regarded as a component of soil organic carbon, yet how small amounts of vertically redistributed pyrogenic carbon influence organo mineral interfaces in subsoils remains unresolved. Here we combine a ten year field ageing experiment along a 200 cm calcareous soil profile in China with electrochemical assays, spectroscopy and nanoscale microscopy to link pyrogenic carbon electron transfer capacity to mineral association. Redistributed pyrogenic carbon retains electron accepting and donating capacities in subsoils despite low concentrations and exhibits faster electron transfer kinetics. This retention reflects oxidative surface transformation, enriching quinone and phenolic redox moieties and mineral complexing oxygen groups. Nanoscale observations show oxidised subsoil pyrogenic carbon surfaces with organo mineral coatings associated with iron and calcium bearing phases, consistent with a coupled redox and sorptive interface rather than passive presence alone. These findings suggest that field-aged pyrogenic carbon contributes to redox coupled mineral stabilisation in calcareous subsoils. In calcareous alkaline soils, pyrogenic carbon acquires and retains persistent redox-coupled mineral stabilisation and faster electron transfer kinetics that remains expressed after vertical redistribution, based on a ten-year long field experiment in China.

Abstract The effects of biochar on methane emissions from soils are well understood. However, biochar effects on methane production from livestock have received less attention. In this study, a biochar-mineral supplement for livestock was developed by pyrolyzing a mixture of wheat straw, aluminosilicates, iron sulfate, and zinc oxide at 600 ℃. The supplement was then activated using peracetic and propionic acids, and potassium nitrate. The activated biochar-mineral supplement was characterized using analytical techniques. A high surface area, a high concentration of oxygen-containing functional groups, and a high concentration of free radicals, associated with O and Fe unpaired electrons, assisted the supplement with catalysing the oxidation of methane. Microstructural analysis of the supplement suggested the formation of organo-mineral phases, rich in C, O, Fe, Si, Al, K and Ca, indicating that the biochar reacted with mineral additives to preserve them. To assess the potential of the supplement to reduce methane produced form livestock, an in vitro batch culture incubation was conducted (n = 3) with rumen fluid sourced from Holstein–Friesian steers. The supplement was incubated at inclusion rates of 0% (control), 1.5%, 4.0% and 6.0% of dry matter (DM), with a Rhodes grass hay substrate. Compared to the control, the supplement reduced cumulative gas production by 10.1% and 12.7% and methane production by 19.03% and 29.32% after 48 h when included at 4.0% and 6.0% DM (P < 0.05), respectively, without causing any detrimental impacts on fermentation parameters. The supplement assisted with reducing the concentration of dissolved mineral nutrients, such as P and Mg, when included at 4.0% and 6.0% DM (P < 0.05). Graphical abstract

A Ti‐10V‐3Al‐3Fe metastable β Ti alloy is strained under three‐point bending conditions according to the ASTM E290‐14 standard. A combination of electron backscatter diffraction (EBSD) mapping and high‐resolution scanning transmission electron microscopy (STEM) is used to investigate the microstructural response to flexural stress. Results reveal a delayed formation of the deformation products, due to the load‐bearing capacity of the constituent voids. The deformation products are confined in narrow bands on either side of the fracture surface. {332}⟨113⟩ twinning system is identified as the primary deformation mode followed by the formation of α ″ martensite both in β matrix and β twins. Accommodation of the microscopic strain arising from the development of α ″ structure and β ‐twinning triggers the formation of fine deformation‐induced ω plates, which are observed predominantly at the interfacial plane of β / β twin and β / α ″, and also in the interior of the β twins.

Molybdenum carbides are promising low-cost electrocatalysts for electrolyzers, fuel cells, and batteries. However, synthesis of ultrafine, phase-pure carbide nanoparticles (diameter < 5 nm) with large surface areas remains challenging due to uncontrollable agglomeration that occurs during traditional high temperature syntheses. This work presents a scalable, physical approach to synthesize molybdenum carbide nanoparticles at room temperature by ion implantation. By tuning the implantation conditions, various molybdenum carbide phases, stoichiometries, and nanoparticle sizes can be accessed. For instance, molybdenum ion implantation into glassy carbon at 30 keV energy and to a fluence of 9 × 1016 at cm-2 yields a surface η-Mo3C2 with a particle diameter of (10 ± 1) nm. Molybdenum implantation into glassy carbon at 60 keV to a fluence of 6 × 1016 at cm-2 yields a buried layer of ultrafine γ'-MoC/η-MoC nanoparticles. Carbon ion implantation at 20 keV into a molybdenum thin film produces a 40 nm thick layer primarily composed of β-Mo2C. The formation of nanoparticles in each molybdenum carbide phase is explained based on the Mo-C phase diagram and Monte-Carlo simulations of ion-solid interactions invoking the thermal spike model. The approaches presented are widely applicable for synthesis of other transition metal carbide nanoparticles as well.

Tungsten carbides have an electronic density of states near the Fermi level similar to platinum and are predicted to exhibit high intrinsic activity toward the hydrogen evolution reaction (HER). However, traditional fabrication routes typically require high synthesis temperatures, resulting in undesirable agglomeration and losses in electrocatalytic performance. Herein, we demonstrate the use of thermal spikes, a high-energy transient phenomenon resulting from ion implantation, to synthesize tungsten carbide nanoparticle films without thermal annealing. By precisely controlling the carbon fluence implanted into smooth tungsten thin-film substrates, beta-W2C, gamma-WC, and delta-WC were selectively synthesized. Despite their low surface area, the tungsten carbide films possessed a high density of grain boundaries resulting in excellent intrinsic HER activity and stability (TOF = 11 H-2 s(-1), 10 mA cm(-2) for 12 h). These results confirm that ion implantation is a promising approach for synthesizing tungsten carbide nanoparticle films with high intrinsic activity toward HER.

We report the synthesis of core-shell Ni-Pt nanoparticles (NPs) with varying degrees of crystallographic facets and surface layers rich in Pt via a seed-mediated thermolytic approach. Mixtures of different surfactants used during synthesis resulted in preferential surface passivation, which in turn dictated the size, chemical composition, and geometric evolution of these PtNi NPs. Electrochemical investigations of these pristine core-shell Ni-Pt structures in the oxygen reduction reaction (ORR) show that their catalytic functionalities outperform the commercial Pt/C reference catalyst. The enhanced electrocatalytic ORR performances of these Pt-based PtNi NPs are correlated with the weakened oxygen binding strength or surface-adsorbed hydroxyl (OH) species on active Pt surface sites induced by the downshift of the d-band center as a result of compressive strain effects. Our studies offer a robust synthetic approach for the development of core-shell nanostructures for enhanced ORR catalysis.

Biochar amendments add persistent organic carbon to soil and can stabilize rhizodeposits and existing soil organic carbon (SOC), but effects of biochar on subsoil carbon stocks have been overlooked. We quantified changes in soil inorganic carbon (SIC) and SOC to 2 m depth 10 years after biochar application to calcareous soil. The total soil carbon (i.e., existing SOC, SIC, and biochar-C) increased by 71, 182, and 210% for B30, B60, and B90, respectively. Biochar application at 30, 60, and 90 t ha-1 rates significantly increased SIC by 10, 38, and 68 t ha-1, respectively, with accumulation mainly occurring in the subsoil (below 1 m). This huge increase of SIC (mainly CaCO3) is ∼100 times larger than the inorganic carbon present in the added biochar (0.3, 0.6, or 0.9 t ha-1). The benzene polycarboxylic acid method showed that the biochar-amended soil contained more black carbon particles (6.8 times higher than control soil) in the depth of 1.4-1.6 m, which provided the direct quantitative evidence for biochar migration into subsoil after a decade. Spectral and energy spectrum analysis also showed an obvious biochar structure in the biochar-amended subsoil, accompanied by a Ca/Mg carbonate cluster, which provided further evidence for downward migration of biochar after a decade. To explain SIC accumulation in subsoil with biochar amendment, the interacting mechanisms are proposed: (1) biochar amendment significantly increases subsoil pH (0.3-0.5 units) 10 years after biochar application, thus forming a favorable pH environment in the subsoil to precipitate HCO3-; and (2) the transported biochar in subsoil can act as nuclei to precipitate SIC. Biochar amendment enhanced SIC by up to 80%; thus, the effects on carbon stocks in subsoil must be understood to inform strategies for carbon dioxide removal through biochar application. Our study provided critical knowledge on the impact of biochar application to topsoil on carbon stocks in subsoil in the long term.

Porous carbon-rich supplements can enhance animal health, improve rumen fermentation characteristics and reduce methane emitted from livestock. In this study, an activated carbon-mineral supplement (ACM) was produced by pyrolyzing a mixture of wheat straw, diatomite, aluminosilicates, iron sulfate, zinc oxide and copper sulfate at a temperature of 600 ℃. The supplement was then activated using peracetic and propionic acids, and potassium nitrate. The supplement exhibited a high surface area, a high concentration of oxygen-containing functional groups and a high concentration of free radicals capable of catalysing the oxidation of methane. Microstructural analysis suggested the formation of organo-mineral phases, rich in C, O, Fe, K, Na, Ca and aluminosilicates, that could assist with reducing methane emissions. To examine the effect of the supplement on fermentation parameters and methane production, a 48h in vitro batch culture incubation was conducted with rumen fluid sourced from three Holstein-Friesian steers. The supplement was incubated at application rates of 0 (control), 1.5, 4.0 and 6.0% of dry matter (DM), with a Rhodes grass hay substrate. Compared to the control, the supplement reduced cumulative gas production by 10.1% and 12.7% and methane production by 19.03% and 29.32% after 48h when included at 4.0 and 6.0% DM (P<0.05), respectively. The supplement, however, did not have a significant effect on total volatile fatty acid (VFA) production and in vitro dry matter digestibility (IVDMD) (P>0.05). The ACM assisted with reducing the concentration of dissolved mineral nutrients, such as Ca (P>0.05), P and Mg, when included at 4.0 and 6.0% DM.

In this study, we investigate the properties of ferrimagnetic ${\mathrm{Tb}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$ (TbIG) thin films grown on ${\mathrm{Gd}}_{3}{\mathrm{Ga}}_{5}{\mathrm{O}}_{12}$ (GGG) substrates using the pulsed laser deposition technique. Some of the films are capped with a thin platinum (Pt) layer. We observe a strong temperature-dependent anomalous Hall effect in the films, with sign reversals at the ferrimagnetic compensation temperature $(\ensuremath{\sim}240\phantom{\rule{0.16em}{0ex}}\mathrm{K})$ and lower temperatures. X-ray diffraction and scanning transmission electron microscopy (STEM) confirm the high crystalline quality and smooth surfaces of the films, while the Pt layer is found to be polycrystalline. Polarized neutron reflectometry reveals a weak magnetic moment confined to the TbIG layer, and an interfacial magnetic layer at the substrate-film boundary appears at low temperatures (below 10 K). This observation is supported by STEM-energy dispersive x-ray mapping, which indicates a chemical difference in the ratio of Gd:Ga at the TbIG/GGG interface. Unlike YIG/GGG interfaces, the TbIG/GGG interface does not exhibit magnetic dead layers. Additionally, a small, induced magnetization is detected in the Pt heavy metal layer at low temperature, with ferromagnetic coupling to the garnet, potentially influencing the anomalous Hall effect.

Molybdenum carbides are promising low-cost alternatives to platinum-based catalysts for the hydrogen evolution reaction (HER). In spite of decades of research, scalable and reliable synthetic routes toward electrochemically active molybdenum carbide surfaces have yet to be discovered. Herein, we demonstrate the application of an industrial surface modification technique that is based on low-energy implantation to synthesize films containing the phases gamma-MoC, gamma '-MoC, eta-MoC, beta-Mo2C, and beta '-Mo2C with excellent intrinsic HER activity. Smooth molybdenum substrates (<1.5 nm) were selected for the carbon implantation studies. Grazing incidence X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution scanning transmission electron microscopy results verified the successful formation of molybdenum carbides and the high density of non-aligned phases or grain boundaries in the films. By varying the implantation energy and fluence, selective production of specific molybdenum carbides could be achieved. Specifically, a transition from beta-Mo2C toward eta-MoC was observed with increasing carbon fluence. Despite their small surface area, the molybdenum carbide films were able to efficiently drive HER in 0.5 M H2SO4 with overpotentials as low as 262 mV at 10 mA cm(-2). For the best catalyst, a high turnover frequency (TOF, 18 H-2 s(-1)) and a low Tafel slope (58 mV dec(-1)) were realized. These results encourage the wider use of ion implantation methods for the synthesis of transition metal carbide-based electrocatalysts for HER and other applications.

Iron-enriched biochar has excellent adsorption capacity for contaminants, which is a sustainable multifunctional potential material to mitigate environmental pollution. Both biochar and Fe (hydr)oxides are important materials for accumulating and preserving soil organic carbon. However, it is unclear that the potential of iron-enriched biochar for mitigating CO2 emission from contaminated soil. In this study, soil incubation and extraction experiments were conducted to determine the effects and mechanisms of goethite-enriched wheat straw biochars (GWBs) prepared at two pyrolysis temperatures (GWB450 and GWB600) on mitigation of CO2 emissions in arsenic (As) contaminated soil. The results showed that compared to the control, GWBs significantly reduced the soil available arsenic (As), decreased soil Eh, and promoted the water stability of soil aggregates (<1mm). GWBs also regulated bacterial community structures, and efficiently improved microbial carbon use efficiency (CUE) in contaminated soil, thereby significantly reducing CO2 emission by 37.2 %-40.9 % in 37 days. Spectroscopic and microscopic analysis indicated that microbial colonization widely occurred on the surfaces of the goethite-enriched biochar, and promoted the formation of organo-mineral layers, which resulted in the significant decrease in the CO2 emission. These findings enhance the understanding of the mechanisms of soil carbon sequestration induced by metal-enriched biochar and indicate a new strategy of biochar-based multifunctional soil amendment that can mitigate heavy metal pollution and reduce CO2 emission simultaneously in contami-nated soils.

In this study, we investigate the properties of ferrimagnetic Tb3Fe5O12 (TbIG) thin films grown on Gd3Ga5O12 (GGG) substrates using the pulsed laser deposition technique. Some of the films are capped with a thin platinum (Pt) layer. We observe a strong temperature-dependent anomalous Hall effect in the films, with sign reversals at the ferrimagnetic compensation temperature (similar to 240 K) and lower temperatures. X-ray diffraction and scanning transmission electron microscopy (STEM) confirm the high crystalline quality and smooth surfaces of the films, while the Pt layer is found to be polycrystalline. Polarized neutron reflectometry reveals a weak magnetic moment confined to the TbIG layer, and an interfacial magnetic layer at the substrate-film boundary appears at low temperatures (below 10 K). This observation is supported by STEM-energy dispersive x-ray mapping, which indicates a chemical difference in the ratio of Gd:Ga at the TbIG/GGG interface. Unlike YIG/GGG interfaces, the TbIG/GGG interface does not exhibit magnetic dead layers. Additionally, a small, induced magnetization is detected in the Pt heavy metal layer at low temperature, with ferromagnetic coupling to the garnet, potentially influencing the anomalous Hall effect.

The current study investigates the therapeutic and optical properties of bismuth oxide (Bi2 O3 ) particles for selective melanoma therapy and prevention. The Bi2 O3 particles were prepared using a standard precipitation method. The Bi2 O3 particles induced apoptosis in human A375 melanoma cells but not human HaCaT keratinocytes or CCD-1090Sk fibroblast cells. This selective apoptosis appears to be associated with a combination of factors: increased particle internalization (2.29 ± 0.41, 1.16 ± 0.08 and 1.66 ± 0.22-fold of control) and enhanced production of reactive oxygen species (ROS) (3.4 ± 0.1, 1.1 ± 0.1 and 2.05 ± 0.17-fold of control) in A375 cells compared to HaCaT and CCD-1090SK cells, respectively. As a high-Z element, bismuth is also an excellent contrast agent for computer tomography, which renders Bi2 O3 a theranostic material. Moreover, Bi2 O3 displays high UV absorption and low photocatalytic activity compared to other semiconducting metal oxides, which opens further potential fields of application as a pigment or as an active ingredient in sunscreens. Overall, this study demonstrates the multifunctional properties of Bi2 O3 particles surrounding the treatment and prevention of melanoma.

Axonemal dyneins are gigantic motor enzymes indispensable for proper ciliary and flagellar motility in eukaryotes including Chlamydomonas. These axonemal dyneins convert the chemical energy of ATP to mechanical force to drive ciliary beating. Here we describe discoveries made using Chlamydomonas that first revealed the complex pathways through which axonemal dyneins are preassembled in the cytoplasm, transported into ciliary/flagellar compartments, and docked onto axonemes, and we summarize current information on the many axonemal dynein assembly factors involved in these processes. In addition, we discuss both similarities and differences between dynein assembly mechanisms in Chlamydomonas compared with other eukaryotes that have motile cilia, explore unexpected links between dynein preassembly and human diseases that were revealed through research using Chlamydomonas, and highlight remaining questions about axonemal dynein assembly mechanisms that may be solved through further studies using this model organism.

The conducting boundary states of topological insulators appear at an interface where the characteristic invariant ℤ 2 switches from 1 to 0. These states offer prospects for quantum electronics; however, a method is needed to spatially-control ℤ 2 to pattern conducting channels. It is shown that modifying Sb 2 Te 3 single-crystal surfaces with an ion beam switches the topological insulator into an amorphous state exhibiting negligible bulk and surface conductivity. This is attributed to a transition from ℤ 2 = 1 → ℤ 2 = 0 at a threshold disorder strength. This observation is supported by density functional theory and model Hamiltonian calculations. Here we show that this ion-beam treatment allows for inverse lithography to pattern arrays of topological surfaces, edges and corners which are the building blocks of topological electronics.

Two-Dimensional (2D) III-V nitrides are anticipated to exhibit exceptional material properties with wide-ranging technological significance. We report, ion beam synthesis of buried 2D Aluminium Gallium Nitride structures with enhanced piezoelectric modulus. We propose three criteria for the formation of 2D AlGaN layers by ion implantation. The 2D layers were synthesized by Xe implantation into epitaxially grown, strain-free Al0.5Ga0.5N thin films and their presence was confirmed by scanning transmission electron microscopy. Alternating planar and buckled 2D III-Nitride layers in conjunction with a rapid change of polarity of the buckled layer confirms the weak interaction between the individual layers. Rutherford backscattering, in conjunction with piezoelectric force microscopy was used to identify the optimum Xe dose to induce maximum enhancement of piezoelectric modulus. Our results are supported by X-ray diffraction to quantify the macroscopic strain of the implanted film and Monte-Carlo simulations of ion-solid interactions. Fabrication of this material on a large scale may lead to highly efficient energy harvesters, communication devices, power devices and photocatalytic water splitting technologies.

Zeolite-supported metal nanocluster catalysts have attracted significant attention due to their broad application in heterogeneously catalyzed reactions. The preparation of highly dispersed metal catalysts commonly involves the use of organic compounds and requires the implementation of complicated procedures, which are neither green nor deployable at the large scale. Herein, we present a novel facile method (vacuum-heating) which employs a specific thermal vacuum processing protocol of catalysts to promote the decomposition of metal precursors. The removal of coordinated H2O via vacuum-heating restricts the formation of intermediates (metal-bound OH species), resulting in catalysts with a uniform, metal nanocluster distribution. The structure of the intermediate was determined by in situ Fourier transform infrared, temperature-programmed decomposition, and X-ray absorption spectroscopy (XAS) measurements. This alternative synthesis method is eco-friendly and cost-effective as the procedure occurs in the absence of organic compounds. It can be widely used for the preparation of catalysts from different metal species (Ni, Fe, Cu, Co, Zn) and precursors and is readily scaled-up.

Exploring platinum (Pt)-solute nanoparticles (NPs) with multifaceted geometries, multifunctionality, and extended stability is key for several electrocatalytic applications. Here, we demonstrate that Pt-based alloy NPs modified with molybdenum (Mo) exhibit superior electrocatalytic properties compared with pure Pt NPs. Electrocatalytic testing of these Mo-modified Pt nanoalloys shows excellent catalytic performance in the hydrogen evolution reaction (HER), the oxygen reduction reaction (ORR), and the methanol oxidation reaction (MOR). We show that the catalytic functionalities in the ORR and the MOR achieved by the Mo-modified Pt nanoalloys are 15-25 times greater than the standard commercial Pt/C nanocatalyst. These nanoalloys also show enhanced resistance to poisoning by carbon monoxide (CO) adlayers and stability after accelerated durability tests (ADTs). We associate the origin of these exceptional electrocatalytic performances of the Pt-solute-Mo nanoalloys with their high degree of concavity, variations in vertex chemistry, and Pt enrichment along the corners and edges. Our findings offer a facile synthetic approach for the synthesis of Pt-solute nanoalloys as high-performance multifunctional electrocatalysts.

The unexpected growth of highly aligned and optically polarizing metallic fins during physical vapor deposition under modestly oblique conditions is investigated. The fins exhibit nanoscale dimensions and are formed when Al is co-sputtered with any of V, Cr, Nb, Mo, Ta, W, Ru, Fe, Ni, Pt, Zr, Mg, and Ti. It is proposed that the phenomenon is caused by anomalously low atomic mobility in the alloys and intermetallic compounds formed by co-depositing with Al. In contrast, when Cu, Ag, and Au (which diffuse more rapidly in Al) are deposited, no fins form. There is a sharp visible transition in optical properties as the ratio of Al to other element is decreased: the color of the sample changes from black to silver-white for compositions containing less than about 55 atom % Al. The region over which the color change occurs is associated with a very strongly polarized reflectance. Cross-sectional elemental mapping and Monte Carlo simulations suggest that growth of the fins may be nucleated by Al hillocks and enhanced by shadowing effects. The diversity of suitable metals makes this a versatile technique for producing nanoscale polarizing surfaces suitable for high-flux and high-temperature applications.

Good specimen quality is a key factor in achieving successful scanning transmission electron microscope analysis. Thin and damage-free specimens are prerequisites for obtaining atomic-resolution imaging. Topological insulator single crystals and thin films in the chalcogenide family such as Sb2Te3 are sensitive to electron and ion beams. It is, therefore, challenging to prepare a lamella suitable for high-resolution imaging from these topological insulator materials using standard focused ion-beam instruments. We have developed a modified method to fabricate thin focused ion-beam (FIB) lamellae with minimal ion-beam damage and artifacts. The technique described in the current study enables the reliable preparation of high-quality transmission electron microscope (TEM) specimens necessary for studying ultra-thin surface regions. We have successfully demonstrated that the careful selection of FIB milling parameters at each stage minimizes the damage layer without the need for post-treatment.